I have owned both the Vortex and Phoenix and did not have any problems with reaching the safety on either crossbow. I sold my Vortex only because the stock felt too short for my long arms and it just wasn't as comfortable to shoulder as my Phoenix with it's longer stock.
I don't like a thumbhole stock for that reason. With the ambi stock I can easily sight on a target then release the safety with my thumb without disturbing my sight picture or grip. With a thumbhole I have to break my concentration to get the safety released.
I really like the fit of mine. It's a bit shorter and affords a very comfortable, yet firm grip. Really appreciated it when my hand slipped from the rain-soaked forearm, 15 feet up in a tree stand. Reaching for the safety not an issue. I put the safety on each time the bow is cocked when practicing, and release it just before the shot. It's second nature now.